Patent application title: FAN WITH SOFT START FUNCTION

Abstract:

A bathroom ventilator fan with the soft-start function includes an
impeller and a motor. The motor is coupled to the impeller for driving
the impeller to rotate. The motor has a control module for driving and
controlling the rotation speed of the motor according to a soft-start
signal. The soft-start signal includes a soft-start section and a
target-driving section. The control module slowly increases the rotation
speed of the motor from the soft-start section to reach the
target-driving section.

Claims:

1. A fan with a soft-start function, comprising:an impeller; anda motor
coupled to the impeller for driving the impeller to rotate, wherein the
motor comprises a control module for driving and controlling a rotation
speed of the motor according to a soft-start signal, the soft-start
signal comprises a soft-start section and a target-driving section, and
the control module slowly increases the rotation speed of the motor from
the soft-start section to reach the target-driving section.

2. The fan according to claim 1, wherein the soft-start signal further
comprises an initial rotation-speed section, and the control module keeps
the rotation speed of the motor at an initial rotation speed according to
a rotation speed of the initial rotation-speed section before the
rotation speed of the motor is increased.

3. The fan according to claim 1, wherein a power source is provided to
apply power to the motor.

4. The fan according to claim 3, wherein the power source is a DC power
source or an AC power source.

5. The fan according to claim 4, wherein the AC power source is converted
into a DC power source through an AC/DC converter.

6. The fan according to claim 5, wherein the AC/DC converter comprises a
rectification module.

7. The fan according to claim 6, wherein the rectification module is a
rectification circuit.

8. The fan according to claim 6, wherein the AC/DC converter further
comprises a voltage-drop module coupled to the rectification module.

9. The fan according to claim 8, wherein the voltage-drop module is a
voltage-drop circuit.

10. The fan according to claim 4, wherein the DC power source is decreased
to a work voltage of the motor through a voltage-drop module.

11. The fan according to claim 10, wherein the voltage-drop module is a
voltage-drop circuit.

12. The fan according to claim 1, wherein the soft-start signal is
generated by the control module.

13. The fan according to claim 12, wherein the control module adjusts a
slope of the soft-start section of the soft-start signal.

14. The fan according to claim 1, wherein the control module is a micro
control unit (MCU).

15. The fan according to claim 1, wherein the soft-start signal is
generated by an external device and then transmitted to the control
module.

16. The fan according to claim 15, wherein the external device is a
soft-start circuit.

17. The fan according to claim 1, wherein the soft-start section is
connected to the target-driving section smoothly.

18. The fan according to claim 1, wherein the soft-start section is a
linear curve or a second-degree curve.

19. The fan according to claim 1, wherein a noise raising rate of the fan
according to the soft-start section is not larger than 2 dB per second.

20. The fan according to claim 1, which is a DC fan, an AC fan, an
electrically commutated fan (EC fan), or a bathroom ventilator fan.

[0003]The present invention relates to a fan and in particular to a
bathroom ventilator fan with a soft-start function.

[0004]2. Related Art

[0005]The bathroom is usually equipped with the bathroom ventilator fan.
When the user turns on the switch, the bathroom ventilator fan starts to
generate airflows in the bathroom and thus carry the bad smell or
moisture out.

[0006]However, the conventional bathroom ventilator fan does not have the
soft-start function. Thus, once the bathroom ventilator fan is switched
on, it will rotate at full speed within a very short time. In this case,
the user can obviously hear the noise caused by the bathroom ventilator
fan. If the noise raising rate of the bathroom ventilator fan reaches
about 10 dB per second, the noise will make the user feel uncomfortable.

[0007]In addition, to switch on the bathroom ventilator fan from still
state to full speed state requires a very large start-up current. Thus,
the inrush current, voltage spike or spike noise may occur in the
starting moment when switching on the bathroom ventilator fan. Moreover,
the arc (electric arc phenomenon) may be generated to damage the bathroom
ventilator fan.

[0008]Furthermore, the electric power for driving the conventional
bathroom ventilator fan is usually provided by the city electric power
system. However, the city electric power system provides the AC power
supply, so that the fan powered by the AC power supply usually consumes
relatively more energy, which leads to larger power consumption.

SUMMARY OF THE INVENTION

[0009]In view of the foregoing, the present invention is to provide a fan
with the soft-start function that can reduce the noise and prevent the
inrush current, voltage spike or spike noise, thereby increasing the
product reliability, extending the life time of the product and reducing
the power consumption.

[0010]To achieve the above, the present invention discloses a fan with the
soft-start function. The bathroom ventilator fan includes an impeller and
a motor. The motor is coupled to the impeller and drives the impeller to
rotate. The motor includes a control module for driving and controlling a
rotation speed of the motor according to a soft-start signal. The
soft-start signal includes a soft-start section and a target-driving
section. The control module slowly increases the rotation speed of the
motor from the soft-start section to reach the target-driving section.

[0011]As mentioned above, the fan of the present invention drives and
controls the rotation speed of the motor according to the soft-start
signal, so that the rotation speed of the bathroom ventilator fan can be
increased slowly to the target rotation speed. Compared with the prior
art, the present invention can reduce the noise and prevent the inrush
current, voltage spike or spike noise, thereby increasing the product
reliability and extending the life time of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]The present invention will become more fully understood from the
subsequent detailed description and accompanying drawings, which are
given by way of illustration only, and thus are not limitative of the
present invention, and wherein:

[0013]FIG. 1 is a schematic illustration showing a bathroom ventilator fan
with the soft-starting function according to an embodiment of the present
invention;

[0014]FIGS. 2A and 2B are schematic illustrations showing the bathroom
ventilator fan powered by the DC power source and the AC power source;

[0015]FIG. 3 is a circuit diagram of the bathroom ventilator fan of the
present invention; and

[0016]FIGS. 4A and 4B are schematic illustrations showing the soft-start
signal of the bathroom ventilator fan of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017]The present invention will be apparent from the following detailed
description, which proceeds with reference to the accompanying drawings,
wherein the same references relate to the same elements.

[0018]With reference to FIG. 1, a bathroom ventilator fan 1 with the
soft-starting function according to an embodiment of the present
invention includes an impeller 11 and a motor 12. The motor 12 is coupled
to the impeller 11 and drives the impeller 11 to rotate. The motor 12
includes a main body 121 and a controlling module 122 coupled to the
motor body 121. The types of the impeller 11 and motor 12 are not limited
to the present embodiment. The impeller 11 includes a hub and a plurality
of blades (not shown in the figures), and the blades are disposed around
the hub. The main body 121 of the motor 12 includes a stator and a rotor,
and the motor 12 drives the impeller 11 to rotate. The controlling module
122 can be a micro control unit (MCU).

[0019]Referring to FIGS. 2A and 2B, a power source, such as a DC power
source SDC or an AC power source SAC, is provided to apply
power to the motor 12. As shown in FIG. 2A, when the power source is a DC
power source SDC, a voltage-drop module 211 is needed to decrease
the DC power source SDC to the work voltage SW of the motor 12.
As shown in FIG. 2B, when the power source is an AC power source
SAC, an AC/DC converter 21 is needed to convert the AC power source
SAC into a DC power source. The AC/DC converter 21 includes a
voltage-drop module 211 and a rectification module 212 coupled to the
voltage-drop module 211. The rectification module 212 can convert the
input AC power source SAC to the DC power source SDC. Then, the
voltage-drop module 211 decreases the DC power source SDC to the
work voltage SW of the motor 12 so as to provide the required
electric power for switching on the fan. In the embodiment, the
above-mentioned voltage-drop module 211 and rectification module 212 can
be the commonly used voltage-drop circuit and rectification circuit,
respectively

[0020]After the fan is switched on, the control module 122 generates a
soft-start signal SS for driving and controlling the rotation speed
of the motor. Alternatively, the soft-start signal SS can be
generated by an external device such as a soft-start circuit, and then
the soft-start signal Ss is transmitted to the control module 122.

[0021]To make the present invention more comprehensive, the implemental
circuits of the AC/DC converter 21 and the control module 122 will be
described herein below. With reference to FIGS. 2B and 3, the
rectification module 212 includes an AC filter 2121 and a bridge
rectification circuit 2122. The AC filter 2121 receives the AC power
source SAC and filters the low-band frequency portion of the AC
power source SAC away. The bridge rectification circuit 2122, which
is coupled to the AC filter 2121 and the voltage-drop module 211,
converts the AC power source SAC into the DC power source SDC.
Then, the DC power source SDC is transmitted to the voltage-drop
module 211.

[0022]The voltage-drop module 211 includes a transformer 2111, an optical
coupler 2112, a controller 2113, a switch 2114 and a DC filter 2115. The
transformer 2111 is coupled to the rectification module 212 and decreases
the DC power source SDC to the work voltage S'W of the main
body 121 of the motor. The optical coupler 2112, which is coupled to the
transformer 2111 and the controller 2113, retrieves a feedback signal
SF1 from the transformer 2111 and outputs a coupling signal SL
to the controller 2113. The controller 2113, which is coupled to the
optical coupler 2112 and the switch 2114, outputs a control signal
SC to the switch 2114 according to the coupling signal SL. The
ON/OFF of the switch 2114 can control the transformer 2111 to output
stable work voltage S'W. The DC filter 2115 is coupled to the
transformer 2111, the main body 121 of the motor and the control module
122 for receiving the work voltage S'W. Then, the DC filter 2115
filters the high-band frequency portion of the work voltage S'W and
outputs the work voltage SW, which is the electrical energy for
switching on the main body 121 of the motor and the control module 122.

[0023]The control module 122 includes a voltage-drop converter 1221, a
Hall sensor 1222 and a micro control unit (MCU) 1223. The voltage-drop
converter 1221 is coupled to the DC filter 2115, and is for decreasing
the work voltage SW. Then, the decreased work voltage SW can be
the power source for the Hall sensor 1222 and the MCU 1223. The MCU 1223
is coupled to the main body 121 and generates a soft-start signal SS
for driving and controlling the rotation speed of the motor. When the
motor is started, the magnetic field will change depending on the
rotation speed. The Hall sensor 1222 is coupled to the MCU 1223 and
senses the variation of the magnetic field so as to output a feedback
signal SF2 to the MCU 1223. Then, the MCU 1223 controls the motor
body 121 according to the feedback signal SF2. In addition, the
implemental circuit of FIG. 3 further shows two diodes for preventing the
reverse current.

[0024]FIG. 4A shows a soft-start signal SS of the present embodiment.
The soft-start signal SS includes a soft-start section A and a
target-driving section B. The control module 122 slowly increases the
rotation speed of the motor 12 from the soft-start section A to reach the
target-driving section B. The control module 122 can also adjust a slope
of the soft-start section A. Accordingly, the rate (or time) for the
motor 12 to reach the target-driving second B can be controlled so as to
decrease the noise.

[0025]The soft-start section A can be connected to the target-driving
section B smoothly. Thus, the rotation speed of the motor 12 can be
increased slowly, so that the inrush current, voltage spike or spike
noise caused by the rapidly increased rotation speed can be prevented.
The soft-start section A can be a linear curve or a second-degree curve.
Therefore, when the bathroom ventilator fan 1 is switched on, the
rotation speed of the motor 12 can be increased slowly from zero to the
target rotation speed (such as a full speed). In the present invention,
the noise raising rate of the bathroom ventilator fan 1 during the
soft-start section A is not larger than 2 dB per second.

[0026]FIG. 4B shows another soft-start signal SS1 of the present
embodiment. The soft-start signal SS1 includes a soft-start section
A, a target-driving section B and an initial rotation-speed section C.
The control module 122 keeps the rotation speed of the motor 12 at an
initial rotation speed according to the rotation speed of the initial
rotation-speed section C before the rotation speed of the motor 12 is
increased. Then, the control module 122 slowly increases the rotation
speed of the motor 12 from the soft-start section A to reach the
target-driving section B. In this case, the rotation speed can be
increased stably and slowly, so that the noise can also be decreased.

[0027]Alternatively, the bathroom ventilator fan with the soft-start
function according to the present invention can be a DC fan. An AC/DC
converter 21 is configured to convert the AC power source (city electric
power) into the DC power source. Then, the DC power source is transmitted
to the DC fan for driving the DC fan to rotate. Compared with the AC fan,
the DC fan has the advantage of lower power consumption.

[0028]Moreover, the bathroom ventilator fan with the soft-start function
according to the present invention can be an electrically commutated fan
(EC fan), which has an AC/DC converter for converting the AC power source
(city electric power) into the DC power source. Then, the DC power source
drives the EC fan to rotate. In practice, the additional AC/DC converter
is not needed for the EC fan, so the circuit design can be simplified.

[0029]In summary, the bathroom ventilator fan of the present invention
drives and controls the rotation speed of the motor according to the
soft-start signal, so that the rotation speed of the bathroom ventilator
fan can be increased slowly to the target rotation speed. Compared with
the prior art, the present invention can reduce the noise and prevent the
inrush current, voltage spike or spike noise, thereby increasing the
product reliability and extending the life time of the fan.

[0030]Although the present invention has been described with reference to
specific embodiments, this description is not meant to be construed in a
limiting sense. Various modifications of the disclosed embodiments, as
well as alternative embodiments, will be apparent to persons skilled in
the art. It is, therefore, contemplated that the appended claims will
cover all modifications that fall within the true scope of the present
invention.